JPH0995533A - Colorless transparent polyimide resin material and film or coating film prepared therefrom - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a colorless transparent polyimide resin material which has excellent transparency though it contains no F atom or P atom and has excellent heat resistance and toughness by purifying bicyclo[2,2,2]octanetetracarboxylic acid dianhydride (a) by a specified process and reacting the purified compound with a diamine. SOLUTION: Compound (a) represented by formula I or II is purified by a combination of recrystallization with sublimation, a combination of treatment with active carbon with recrystallization or a combination of treatment with activeted carbon with recrystallization and sublimation, and reacted with a diamine to obtain a colorless transparent polyimide resin material having an average transmittance of 70% or above (as measured on a 15μm-thick film at a wavelength of 250-800nm). Although the diamine is not particularly limited so far as it can imidate compound (a), 4,4'-diaminodiphenylmethane is used for example. The method for obtaining the polyimide is suitably a two-stage polymerization process comprising synthesizing first an amic acid and imidating the acid at high temperatures. The polymerization solvent used is a phenolic solvent or an aprotic polar solvent.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a novel colorless transparent polyimide resin material containing no fluorine atom or phosphorus atom and a solution of polyamic acid as an intermediate thereof in a phenol solvent and / or an aprotic polar solvent, and The present invention relates to a film or coating film using the above resin material.

[0002]

2. Description of the Related Art Polyimide is a functional resin that is widely used in various fields because it has excellent heat resistance.
Generally, it is strongly colored and opaque, which limits its use.

Therefore, studies have been conducted on the improvement of hue and transparency. For example, as disclosed in JP-A-6-271670, a tetracarboxylic dianhydride, which is one component of polyimide, contains a fluorine atom. Compounds have come to be used. However, the tetracarboxylic dianhydride containing a fluorine atom has a drawback that it is uneconomical because the manufacturing method is complicated and the raw material is expensive.

As another method, it is known that triphenyl phosphite is added to improve transparency when synthesizing a polyamic acid as an intermediate of polyimide (Japanese Patent Laid-Open No. 6-116331). However, in this case, there is a problem that the obtained polyimide contains a small amount of phosphorus atom and is not preferable for electronics.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned drawbacks of the prior art, and its object is to provide a novel polyimide containing neither a fluorine atom nor a phosphorus atom in its molecule. Another object of the present invention is to provide a colorless and transparent polyimide resin material and a phenolic solvent and / or aprotic polar solvent solution of polyamic acid, which is an intermediate thereof, and a film or coating film using the above resin material.

[0006]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a polyimide resin material obtained from a purified tetracarboxylic dianhydride having a specific structure and a diamine has a specific UV-visible absorption spectrum. Shows the nature,
The present invention has been completed by finding that the above object can be achieved.

That is, the gist of the present invention is, firstly, the formula [1] or [2].

Embedded image

Embedded image The bicyclo [2.2.2] octanetetracarboxylic acid dianhydride represented by the following is purified by a combination of recrystallization and sublimation, a combination of activated carbon treatment and recrystallization, or a combination of activated carbon treatment, recrystallization and sublimation. In the graph of ultraviolet / visible light absorption spectrum measured by forming a film having a thickness of 15 μm, which is obtained by reacting with diamine
Average transmittance in the wavelength range of 00 nm is 70%
In the colorless and transparent polyimide resin material characterized by the above, secondly, a bicyclo [2.2.2] octanetetracarboxylic dianhydride represented by the above formula [1] or [2] is added. Phenolic solvent of polyamic acid obtained by partially reacting with diamine after purification by combination of recrystallization and sublimation, combination of activated carbon treatment and recrystallization, or combination of activated carbon treatment and recrystallization and sublimation and /
Alternatively, in an aprotic polar solvent solution, which is heated and cured to form a polyimide film having a thickness of 15 μm, in the graph of ultraviolet / visible light absorption spectrum, the average transmittance in the wavelength range of 250 to 800 nm Of 70% or more in a phenolic solvent and / or aprotic polar solvent solution of polyamic acid, and thirdly, in a film or coating film using the above colorless transparent polyimide resin material. .

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The above resin material of the present invention has the same structure as the novel polyimide described in Japanese Patent Application No. 6-119610 by the present inventors, and the polyimide is almost colorless. Although it has a transparency close to, and is quite high, in the present invention, bicyclo [2.
2.2] The octane tetracarboxylic dianhydride is sufficiently purified before use.

Examples of the purification method include purification by a combination of recrystallization and sublimation, purification by a combination of activated carbon treatment and recrystallization, and further purification by a combination of activated carbon treatment, recrystallization and sublimation, preferably recrystallization. It is a purification by the combination of and sublimation. Purification by simple recrystallization is insufficient, and a polyimide resin material having the characteristics in the ultraviolet / visible light absorption spectrum defined by the present invention cannot be obtained. It should be noted that sublimation originally means that the solid does not become a liquid but becomes a vapor (gas) directly. However, in the present invention, the temperature becomes higher than the melting point by heating, and the vapor (gas ) Is included in sublimation.

Bicyclo [2.2.2] octanetetracarboxylic dianhydride represented by the above formula [1] or [2], which is one of the raw materials of the polyimide resin material of the present invention, is
The method described in Japanese Patent Application No. 6-119610 and Japanese Patent Application No. 6-119611 according to the inventions of the inventors of the present invention can be inexpensively and simply manufactured. An outline of an example of the production method is 3,5-cyclohexadiene-obtained by electrolytic reduction of phthalic acid or an alkyl ester thereof.
The trans-1,2-dicarboxylic acid or its alkyl ester is subjected to the Diels-Alder reaction with maleic acid, fumaric acid or its alkyl ester, or maleic anhydride to produce bicyclo [2.2.2] oct-7-ene-
2,3,5,6-tetracarboxylic acid or its alkyl ester, which is hydrogenated and then dehydrated and cyclized.

The diamine which is the other raw material is not particularly limited as long as it can imidize the above tetracarboxylic dianhydride. For example, 4,4'-diaminodiphenylmethane and 4,4'-diamino. Diphenyl ether, 4,4'-diaminodiphenyl sulfone, 4,
4'-diaminodiphenyl sulfide, 4,4'-diaminobenzophenone, 1,4 "-diaminoterphenyl, 1,4-bis (4-aminophenoxy) benzene,
1,3-bis (3-aminophenoxy) benzene, 1,
3-bis (4-aminophenoxy) benzene, bis [4
-(4-Aminophenoxy) phenyl] methane, 2,2
-Bis [4- (4-aminophenoxy) phenyl] propane, bis [4- (4-aminophenoxy) phenyl]
Examples thereof include sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, and 4,4 ′-(p-aminophenoxy) biphenyl. These diamines are
Each of them may be used alone or as a mixture of two or more kinds. Further, these diamines can be used without purification like the above-mentioned tetracarboxylic dianhydride, but it is more preferable if they are purified.

As a method for obtaining a polyimide from the above-mentioned tetracarboxylic dianhydride and diamine, a one-step polymerization method in which polymerization is carried out only at a high temperature, or an amic acid is first synthesized at a low temperature and then an imidization is carried out at a high temperature. Although there is a step polymerization method, in order to obtain a high molecular weight polyimide, the two-step polymerization method is preferable. When the one-step polymerization method is used, the polymerization conditions are 120 to 350 ° C., preferably 1
The temperature is 50 to 300 ° C. for 0.5 to 20 hours, preferably 1 to 15 hours, and in the case of the two-step polymerization method, polyamic acid synthesis is 0 to 120 ° C., preferably 15 to 120 ° C.
More preferably 0.5 to 10 at a temperature of 80 to 110 ° C.
It is carried out for 0 hours, preferably 1 to 100 hours, and then imidization is carried out at 120 to 350 ° C., preferably 150 to 300.
The temperature is 0.5 ° C. for 0.5 to 20 hours, preferably 1 to 10 hours. The first stage polyamic acid synthesis is 0-120 ℃
Within the range of, at the high temperature side, a polyamic acid having a high degree of polymerization is obtained, and by imidizing it, a polymer having a high imidization ratio is obtained, and such a resin material is particularly excellent in toughness. Are better. In order to increase the toughness of polyimide, it is important to increase the degree of polymerization as much as possible at the stage of polyamic acid generation, and to suppress imidization.
In the case of the present invention, 80 to 110 ° C is optimal. To obtain a polyimide having a high degree of polymerization, if the temperature is too high in the first step, imidization will start before the degree of polymerization of the polyamic acid rises, which is not preferable.

In both the one-step polymerization and the two-step polymerization, a phenolic solvent and an aprotic polar solvent are used as the polymerization solvent, and examples of the phenolic solvent include phenol, 4-methoxyphenol and 2,6-dimethylphenol. , M-cresol and the like, and examples of the aprotic polar solvent include N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N, N-dimethylformamide, 1,3-dimethyl-2-imidazolidinium. Non-, dimethyl sulfoxide, caprolactam, tetramethylurea, sulfolane, butyrolactone and the like can be mentioned. These polymerization solvents can be used alone or in combination.

When a polyimide is used as a molded product, for example, a solution of polyamic acid is added to a poor solvent such as acetone to precipitate the polyamic acid, and the solvent is removed from the obtained solid, and further 120 ° C. or higher, preferably Is 1
The imidization reaction may be carried out by heating at a temperature of 50 ° C. or higher and 350 ° C. or lower, and in the case of a polyimide resin having a low glass transition point, molding such as injection molding becomes possible.

When polyimide is formed into a film or a film, for example, a solution of polyamic acid is uniformly applied to a glass plate or the like at room temperature, then placed in a heating furnace, and heated in advance to 90 ° C. or lower under reduced pressure. After removing the solvent, the imidization reaction is performed. In addition, once hardened,
Granular polyimide or the like can also be obtained as a transparent polyimide film or coating film by dissolving it again in a solvent, coating it on, for example, plate glass, and heating in an oven to remove the solvent.

Solvents capable of dissolving polyimide are N, N-
Dimethylacetamide, N-methyl-2-pyrrolidone,
It is a polar solvent such as N, N-dimethylformamide, pyridine, m-cresol, 1,3-dimethyl-2-imidazolidinone or dimethylsulfoxide.

The resin material of the present invention is 250 to 800 nm in the graph of ultraviolet and visible light absorption spectrum measured with a film having a thickness of 15 μm as an index of transparency.
Of the bicyclo [2.2.2] octanetetracarboxylic acid dianhydride, which has an average transmittance of 70% or more within the wavelength range of 1, and uses a commercially available polyimide or a raw material simply recrystallized. This is a value that cannot be reached with polyimide. More specifically, the average transmittance of 70% or more is 0 to 100 on the vertical axis in the graph of the ultraviolet / visible light absorption spectrum of a film having a thickness of 15 μm.
It means that the ratio of the area of the transmission part to the total graph area in the graph in which the abscissa represents the wavelength in the range of 250 to 800 nm is 70% or more.

As described above, the resin material of the present invention having excellent transparency has excellent heat resistance and toughness, which are the original properties of polyimide, and can be used in a wide range of fields, but it does not contain phosphorus atoms. It is particularly suitable for the field of photonics such as an optical switch, which can be used in the field of electronics and is expected to require a response using light in the future, element material for branching an optical fiber, a liquid crystal alignment film, and the like.

[0019]

The present invention will be described in detail with reference to the following examples, but the scope of the present invention is not limited to these examples.

Example 1 In a 30 ml three-necked flask equipped with a rotor stirrer and an Aren condenser installed in an oil bath, diaminodiphenyl ether (hereinafter referred to as D
Abbreviated as DE. ) 4.5 g of an N, N-dimethylacetamide (hereinafter abbreviated as DMAc) solution containing 400 mg (2 mmol) was added, and then 1rC7-bicyclo [2.2.2] octane-2t, 3t, 5c, 6c. -Tetracarboxylic acid dianhydride (which is usually endo-exo
It is called bicyclo [2.2.2] octanetetracarboxylic acid dianhydride, and hereinafter referred to as endo-exo acid dianhydride for simplicity. ) 500 mg (2 mmol) was added in 5 portions. For the 1st to 4th times, after the addition, each was reacted at 90 ° C. for 1 hour, and the 5th time, it was reacted at 90 ° C. for 44 hours, and the solution of polyamic acid (concentration: 0.18 g / ml DMAc) was reacted for 48 hours in total. Obtained.

The raw materials and solvents used in this example were purified by the following method. For DMAc, 30 g of P ₂ O ₅ (diphosphorus pentoxide) was added to 1 l of DMAc, and the mixture was stirred overnight at room temperature (to remove impurities and N, N-dimethylamine). After removing P ₂ O ₅ by decantation, B
After 10 g of aO (barium oxide) was added and the mixture was refluxed for 1 hour, it was distilled under reduced pressure. The molecular sieve 4A was placed therein, and the mixture was stored under a nitrogen atmosphere at room temperature in the dark. The endo-exo acid dianhydride was synthesized by the method described in Japanese Patent Application No. 6-119611, recrystallized using acetic anhydride as a solvent, and further sublimated at 180 ° C. under a reduced pressure of 1 mmHg for purification. DDE was purified by recrystallization using methanol as a solvent and sublimation at 125 ° C. under a reduced pressure of 1 mmHg.

After coating a part of the above polyamic acid solution on a glass plate, the glass plate was transferred to a heating furnace and heated under reduced pressure to 80
Treatment at ℃ for 2 hours to remove solvent, then 250
The polyimide film having a thickness of 15 μm was obtained by performing an imidization reaction by heating at 2 ° C. for 2 hours. In the graph of the ultraviolet / visible light absorption spectrum in which the vertical axis represents the transmittance of 0 to 100% and the horizontal axis represents the wavelength of 250 to 800 nm, the ratio of the transmissive portion to the total area is measured using the film. , 71.9%.
Also, 1660c based on amic acid in the infrared spectrum
Since absorption of m ^-1 was not observed at all, it is considered that this polyimide contains no amic acid moiety at all and the imide ring closure rate is 100%.

The intrinsic viscosity of the polyamic acid measured with the DMAc solution was 0.40 (dl / g), and the glass transition point (TMA method) of the obtained polyimide film was 383 ° C.
Met. Also, length 3 mm, width 2 mm, thickness 20 μm
The tensile strength of the film measured by the TMA apparatus at a pulling rate of 1 mm / min using the test piece of No. 6 was 63.5 MPa. Hereinafter, the tensile strength was measured by the same method.

The above polyamic acid solution (concentration:
0.18 g / ml DMAc) 2 ml was added to a large amount of acetone, and the precipitated precipitate was filtered to remove DMAc from the precipitate.
After removing the acetone solvent and the solvent at 80 ° C. for 2 hours and 250 ° C. for 2 hours, DMAc and acetone were completely removed and the imidization reaction was carried out to obtain 0.33 g of a solid polyimide. As a result of a solubility test of the obtained solid in various solvents, N-methyl-2-
Pyrrolidone, N, N-dimethylformamide, DMA
It was dissolved in c, 1,3-dimethyl-2-imidazolidinone, dimethylsulfoxide, m-cresol, pyridine and concentrated sulfuric acid. Further, the obtained solid polyimide was dissolved again in DMAc to obtain a polyimide film having a thickness of 15 μm in the same manner as above, but it showed the same physical properties as the film obtained directly from the polyamic acid solution.

Example 2 Instead of DDE used in Example 1, a solvent mixture having a benzene: n-hexane ratio of 1: 1 (vol / vol) was used.
After recrystallization twice using the mixed solvent of 1 mmH
An experiment was conducted under exactly the same conditions as in Example 1 except that diaminodiphenylmethane (hereinafter abbreviated as DDM) sublimated at 110 ° C. was used under a reduced pressure of g. The ratio of the area of the transmission part to the total area in the graph of the ultraviolet / visible light absorption spectrum similar to that in Example 1 of the obtained polyimide film having a thickness of 15 μm was 71.5%. The intrinsic viscosity of the polyamic acid measured with the DMAc solution was 0.16 (dl / g), and the glass transition point (TMA method) of the polyimide film was 385 ° C.

Example 3 Instead of the endo-exo acid dianhydride used in Example 1, 1rC purified as in Example 1 was used.
7-bicyclo [2.2.2] octane-2c, 3c, 5
c, 6c-Tetracarboxylic acid dianhydride (this is usually ex
o-exo Bicyclo [2.2.2] octane tetracarboxylic acid dianhydride, which is referred to as exo-e for the sake of simplicity.
It is referred to as xo dianhydride. Example 1 except that the reaction temperature for producing the polyamic acid was 95 ° C.
The experiment was conducted under exactly the same conditions as. The obtained thickness is 15 μm
The ratio of the area of the transmissive portion to the total area in the graph of the ultraviolet / visible light absorption spectrum measured using the polyimide film was 74.0%. The obtained transmittance curve is shown in FIG. The intrinsic viscosity of the polyamic acid measured with the DMAc solution is 0.34 (dl / g), and the glass transition point (TM) measured with the polyimide film.
A method) is 385 ° C, and the tensile strength of the film is 96.4MP.
It was a.

Example 4 Instead of DDE used in Example 1, methanol was used as a solvent and recrystallization was performed twice, and then 1 mm.
1,3-bis (3-aminophenoxy) benzene sublimated at 150 ° C. under reduced pressure of Hg (hereinafter, 1,3-B
Abbreviated as AB. ) Was used, and the experiment was performed under exactly the same conditions as in Example 1. The ratio of the area of the transmission part to the total area in the graph of the ultraviolet / visible light absorption spectrum measured using the obtained polyimide film having a thickness of 15 μm was 78.5%. The obtained transmittance curve is shown in FIG. The intrinsic viscosity of the polyamic acid measured with the DMAc solution was 0.18 (dl / g), the glass transition point (TMA method) of the polyimide film was 211 ° C., and the tensile strength of the film was 57.4 MPa.

Comparative Example 1 In Example 1, endo-exo bicyclo [2.2.
2] An experiment was conducted under exactly the same conditions as in Example 1 except that octane tetracarboxylic dianhydride and DDE were used after recrystallization without sublimation, and a polyimide film having a thickness of 15 μm was obtained. The ratio of the area of the transmission part to the total area in the graph of ultraviolet / visible light absorption spectrum is 6
3.0%. The obtained transmittance curve is shown in FIG.

Comparative Example 2 The ratio of the area of the transmission part to the total area in the graph of the ultraviolet / visible light absorption spectrum measured using a film of Kapton (manufactured by DuPont) having a thickness of 15 μm was 49.2%. It was The obtained transmittance curve is shown in FIG.
Shown in

[0030]

INDUSTRIAL APPLICABILITY The polyimide resin material of the present invention has excellent transparency even though it does not contain any fluorine atom or phosphorus atom, and also has excellent heat resistance and toughness inherent in polyimide, which is economical. It is a resin material useful in a wide range of fields, and is particularly suitable for a film or a coating film. In particular, since it does not contain a phosphorus atom, it is useful in the field of electronics, and in the fields of photonics such as optical switches, element materials for branching optical fibers, and liquid crystal alignment films.

[Brief description of drawings]

FIG. 1 is a graph of ultraviolet / visible light absorption spectra of polyimides produced in Examples 3 and 4 and Comparative Example 1 of the present invention and Kapton used in Comparative Example 2.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ikuzo Nishiguchi 2-7-2 Kusuhaoka, Hirakata City, Osaka Prefecture

Claims (4)

[Claims] 1. A formula [1] or [2]: Embedded image The bicyclo [2.2.2] octanetetracarboxylic acid dianhydride represented by the following is purified by a combination of recrystallization and sublimation, a combination of activated carbon treatment and recrystallization, or a combination of activated carbon treatment, recrystallization and sublimation. In the graph of ultraviolet / visible light absorption spectrum measured by forming a film having a thickness of 15 μm, which is obtained by reacting with diamine
Average transmittance in the wavelength range of 00 nm is 70%
A colorless and transparent polyimide resin material characterized by the above. 2. A combination of recrystallization and sublimation of bicyclo [2.2.2] octanetetracarboxylic dianhydride represented by the formula [1] or [2] according to claim 1, activated carbon treatment and re-treatment. A phenolic solvent and / or an aprotic polar solvent solution of a polyamic acid obtained by partially reacting with a diamine by purifying by a combination of crystals or a combination of activated carbon treatment, recrystallization and sublimation, In a graph of an ultraviolet / visible light absorption spectrum measured by heating and curing the polyimide film having a thickness of 15 μm, the average transmittance in the wavelength range of 250 to 800 nm is 70% or more. A phenolic solvent and / or aprotic polar solvent solution of polyamic acid to be used. 3. The phenolic solvent and / or aprotic polar solvent is phenol, 4-methoxyphenol, 2,6-dimethylphenol, m-cresol,
N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N, N-dimethylformamide, 1,3-dimethyl-2-imidazolidinone, dimethyl sulfoxide,
The solution according to claim 2, which is caprolactam, tetramethylurea, sulfolane or butyrolactone. 4. A film or coating film using the colorless and transparent polyimide resin material according to claim 1.